The institute of electrical and electronics engineers (IEEE) 802.16 standard provides a technique and protocol for supporting broadband wireless access. The standardization had been conducted since 1999 until the IEEE 802.16-2001 was approved in 2001. The IEEE 802.16-2001 is based on a physical layer of a single carrier (SC) called ‘WirelessMAN-SC’. The IEEE 802.16a standard was approved in 2003. In the IEEE 802.16a standard, ‘WirelessMAN-OFDM’ and ‘WirelessMAN-OFDMA’ are further added to the physical layer in addition to the ‘WirelessMAN-SC’. After completion of the IEEE 802.16a standard, the revised IEEE 802.16-2004 standard was approved in 2004. To correct bugs and errors of the IEEE 802.16-2004 standard, the IEEE 802.16-2004/Cor1 was completed in 2005 in a format of ‘corrigendum’.
Hereinafter, a downlink is a communication link from a base station (BS) to a user equipment (UE), and an uplink is a communication link from the UE to the BS.
In general, the BS schedules uplink and downlink radio resources in the wireless communication system. User data or a control signal is carried on the uplink and downlink radio resources. A channel for carrying the user data is referred to as a data channel. A channel for carrying the control signal is referred to as a control channel. Various types of the control signal are required for communication between the BS and the UE. Examples of the control signal required for scheduling of radio resources in a multiple-antenna system include a channel quality indicator (CQI), a rank indicator (RI), a precoding matrix indicator (PMI), etc. The UE transmits the control information (e.g., the CQI, the RI, the PMI, etc.) to the BS. The BS schedules uplink and downlink radio resources according to the control signal received from a plurality of UEs.
In an orthogonal frequency division multiple access (OFDMA) system, a whole frequency band can be divided into several bands, and the control signal can be transmitted for each of the bands. Radio resources may be wasted when the control signal is transmitted for all bands. Thus, a specific band may be selected from the bands so that the control signal is transmitted for only the selected band. In this case, the UE also has to transmit a band bitmap to indicate which band is the selected band. In general, the number of bits of the band bitmap is equal to a total number of bands. That is, if the whole frequency band is divided into 12 bands, the band bitmap can be expressed by 12 bits. Accordingly, there is a need for a method for reducing radio resources required to transmit the band bitmap to the BS by decreasing the number of bits of the band bitmap.